基于铅离子对酚酞-过氧化氢氧化体系催化特性的催化光度检测氡的新方法

New method for the detection of radon of catalytic spectrophotometric based on the catalytic characteristics of lead ion in phenolphthalein and hydrogen peroxide oxidation system

目的氡辐射α、β粒子后形成稳定子体铅。基于铅,建立氡的被动式累积化学采样新方法和催化光度动力学测定新方法。方法氡辐射透过滤膜,衰变形成铅,溶解于吸收体HNO3,氧化成为Pb2+。p H=11时,Pb2+催化H2O2-酚酞反应体系褪色,ΔΑ值与Pb2+浓度(ρ)、氡浓度(CRn)呈现良好的定量关系。应用ΔΑ值计算被动式累积氡的含量。结果 Pb2+对H2O2氧化酚酞催化反应为准一级反应,Ea=83.606 k J/mol。ρ=7.7 ng/ml^200.0 ng/ml时,ΔA=0.002 1ρ+0.32,r=0.999 5;对铅的检出限为2.31 ng/ml。ΔA、氡辐射暴露时间(t)和CRn之间的数学定量关系为ΔA=FCRnt+a,CRn=(ΔA-a)/(Ft)。结论新建立的采样方法和定量检测方法避免了现场的放射性危害。样品溶液可直接测定,不需要处理;仪器设备简单,操作简便,方法灵敏。

Objective Stable daughter lead will be formulated after oc and [3 particles irradiated by radon. New method for the passive and cumulative chemical sampling of radon will be established. And new determination method for catalytic spectropho- tometric of radon wiU be made based upon the catalytic kinetics characteristics of lead ion. Methods Radon radiation entered into the sampling device through the membrane, radiative decay would form lead. Lead was oxidized into Pb2＋ after dissolving in the absorber HNO3. In the NaOH medium （pH=11 ）, phenolphthalein solution was faded because of the oxidization of H2 02. Pb2＋ had strong sensitive catalytic on this reaction. The fading degree of reaction system （ AA value） was linearly correlated with the concentration of Pb2＋ （p） and the cumulative concentration of radon（CRn）. The CRn value could be conducted by applying the AA value or the concentration of Pb2＋ . Results The research shows that the catalytic fading reaction was a pseudo first order reaction, and apparent activation energy Ea = 83. 606 kJ/mol. The linear regression equation was AA = 0. 002 lp ＋ 0.32 with a detection limit of lead was 2.31 ng/ml, r = 0. 999 5 in the range of ρ= 7.7 ng/ml - 200.0 ng/ml. And AA = FCRn t ＋ a, CR, = （AA -a）/（Ft）. The t was the radon exposure time or sampling time. Conclusion The radioactive hazard would be a- voided through newly built sampling method and quantitative detection method. The sampling solution could be directly detected without any treatment. The method had the advantage of simple equipment, convenient operation and high sensitivity.